Typical bolted joints do not stand up to a corrosive sea water environment well. Bolts, especially high strength bolts, corrode quickly and may fail. Bolts are usually unusable after extended submergence in sea water. Crevices in contact with sea water, especially when mating two surfaces of dissimilar materials, undergo severely accelerated corrosion. This is particularly concerning when the joint constitutes a major functional part of equipment that requires maintenance, such as pumps, heat exchangers and pressure vessels.
Sea water submerged pipe connections are typically welded to limit effects of corrosion. However, welding is a permanent connection, which must be destroyed in order to access equipment for service, maintenance and replacement. This is particularly concerning when the joint constitutes a major functional part of the equipment as in pumps, heat exchangers and pressure vessels. Some or all of this equipment must be scraped/rebuilt/recertified prior to reentry to service. For example, pressure vessels require certification to ASME BPV Section VIII whenever welding occurs at vessel connections. This requires an approved authority, time, money, test equipment and a suitable environment.